1. Field of Invention
The present invention relates to a process for producing omega-9 highly unsaturated fatty acid and lipid containing the same by fermentation using a mutant strain in which .DELTA.12 desaturation activity has been decreased or lost, but at Beast one of .notident.5 desaturation activity, .DELTA.6 desaturation activity and chain length elongation activity is elevated.
2. Related Art
Omega-9 highly unsaturated fatty acids, such as 5,8,11-eicosatrienoic acid (referred to as mead acid) and 8,11-eicosadienoic acid, are known to exist as one of the constituent fatty acids of animal tissue that has become deficient in essential fatty acids. However, it has been extremely difficult to isolate and purify them since they are present in extremely small amounts. Since it is possible for these highly unsaturated fatty acids to become precursors of the leucotriene 3 group in the body, considerable expectations have been placed on their physiological activity. Their use for anti-inflammatory, anti-allergic and anti-rheumatic effects has recently been reported (Japanese Unexamined Patent Publication No. 7-41421).
There is therefore a strong desire to develop a method for producing omega-9 highly unsaturated fatty acids in large amounts. A process for producing omega-9 highly unsaturated fatty acid and lipid containing the same was previously completed by performing mutation on microorganisms having the ability to produce arachidonic acid and isolating those microorganisms in which A12 desaturation activity has been decreased or lost (Japanese Unexamined Patent Publication No. 5-91888). However, although it is revolutionary and significant that a process for producing omega-9 highly unsaturated fatty acid and lipid containing the same was developed since such a process had not existed in the past, there was still much room for improvement in yield. Consequently, there has been a strong desire to develop a process for efficiently producing a larger amount of omega-9 highly unsaturated fatty acids.